Replace matches using regex by modifying matched string in swift

Question

Im trying to replace matched strings using regex in swift, my requirement is as below

originalString = "It is live now at Germany(DE)"

i want the string within the (" ") i.eDE to be separated by space i.e. "D E"

so replacedString should be "It is live now at Germany(D E)"

i tried below code

var value: NSMutableString = "It is live now at Germany(DE)"
let pattern = "(\\([A-Za-z ]+\\))"
let regex = try? NSRegularExpression(pattern: pattern)
regex?.replaceMatches(in: value, options: .reportProgress, range: 
NSRange(location: 0,length: value.length), withTemplate: " $1 ")
print(value)

output is It is live now at Germany (DE), i know it's not what is required. here it is based on the template where we cannot modify based on matched string value. Is there any way to achieve this ?

Thanks in advance

Is the format fixed as (+2 letters+)? Try value.replacingOccurrences(of: "(\$[A-Za-z])([A-Za-z]\$)", with: "$1 $2", options: String.CompareOptions.regularExpression, range: nil) — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Aug 6, 2019 at 7:43
@Wiktor, thanks for your response. No it is not fixed with 2 letters it can be more than 2 as well. — Rajesh Rs
– Rajesh Rs, Commented Aug 6, 2019 at 7:51
Ok, so that is always (, then 1 or more spaces or letters and then a ), right? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Aug 6, 2019 at 7:52
Yes, just to give another example "(SOFE)" should be "(S O F E)" — Rajesh Rs
– Rajesh Rs, Commented Aug 6, 2019 at 7:54

Wiktor Stribiżew · Accepted Answer · 2019-08-06 08:07:41Z

2

You may use

var value: NSMutableString = "It is live now at Germany(DE) or (SOFE)"
let pattern = "(?<=\\G(?<!\\A)|\\()[A-Za-z](?=[A-Za-z]+\\))"
let regex = try? NSRegularExpression(pattern: pattern)
regex?.replaceMatches(in: value, options: .reportProgress, range: NSRange(location: 0,length: value.length), withTemplate: "$0 ")
print(value)

Or just

let val =  "It is live now at Germany(DE) or (SOFE)"
let pattern = "(?<=\\G(?<!\\A)|\\()[A-Za-z](?=[A-Za-z]+\\))"
print( val.replacingOccurrences(of: pattern, with: "$0 ", options: .regularExpression, range: nil) )

Output: It is live now at Germany(D E) or (S O F E)

Pattern details

(?<=\\G(?<!\\A)|\\() - a positive lookbehind that matches a location right after ( or at the end of the preceding successful match
[A-Za-z] - matches and consumes any ASCII letter
(?=[A-Za-z]+\\)) - a positive lookahead that matches a location that is immediately followed with 1+ ASCII letters and then a ) char.

The $0 in the replacement inserts the whole match value back into the resulting string.

edited Aug 6, 2019 at 8:07

answered Aug 6, 2019 at 8:02

Wiktor Stribiżew

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2 Comments

Rajesh Rs Over a year ago

It works. But i have a query, which part of the regex is adding space " " between the characters?. Sorry if it is a silly question as my understanding of RegEx is that of a beginner

Wiktor Stribiżew Over a year ago

@RajeshRs withTemplate: "$0 " / with: "$0 " - do you see the space now? Regex never inserts or add anything, regex patterns are used to search for strings meeting some pattern. The replacement patterns are used to add/insert chars to/instead of matches.

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